Area Forecast Discussion
Issued by NWS La Crosse, WI

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711
FXUS63 KARX 191926
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
230 PM CDT Sat Oct 19 2019

.SHORT TERM...(Tonight through Tuesday)
Issued at 230 PM CDT Sat Oct 19 2019

Currently...band of clouds and showers making steady progress
eastward, associated with a north-south running cold front and upper
level shortwave trough. Current satellite/radar trends pulls most of
the clouds/pcpn east of the forecast area by 00z.

Models remain in lock-step with taking an upper level trough
eastward out of the southern rockies Sunday night, strengthening and
sharpening the trough as it moves through the plains and then across
the northern great lakes by early Tue morning. The storm system
becomes vertically stacked as it does with sfc low generally favored
to stay just north of the local forecast area. +100 kt 300 mb jet
having a healthy hand in strengthening the system as it drives under
the trough, then lifts it northeast into southeast Canada for the
beginning of next week. Left exit region of the jet will also aid in
lift as it swings through the local area.

Low level warm air advective wing will lead the system into the
region, with a band of showers moving in later Sunday evening. The
associated cold front shifts in for Monday morning, with 850 mb
moisture transport/low level jet helping it fire off more showers as
it swings through. Both the GFS and NAM suggest there could be
enough elevated instability aloft on Monday for isolated storms. No
suggestions of strong, let alone severe storms.

Southern parts of the forecast area then look to come under the
influence of the mid level dry slot later Mon morning through the
afternoon. Cyclonic flow and bits of upper level energy will keep
showers going on the backside of the departing low, mostly from the
I-90 corridor northward. With the low taking a slower pace
northeast, showers will likely linger across the north through Tue.
Current temp profiles would keep the pcpn as rain (locally).


.LONG TERM...(Wednesday through Saturday)
Issued at 230 PM CDT Sat Oct 19 2019

Colder air will move in post the departing early week low pressure
system, with northwest flow a loft providing a steady push
south/southeast of colder Canadian air. A return to below normal
temps are expected. Shortwave ridging a loft could bring a brief
break in the colder conditions for the weekend.

Current trends in the overall pattern is favoring a dry period for
the later half of the new week. A few pieces of shortwave energy
could ripple along the flow on Wed, bringing some pcpn chances,
mostly south. Otherwise, the next trough of note looks to scoot west-
east along the U.S/Canadian border next weekend, with most of the
upper level energy holding there. Associated sfc boundary would trek
through the Upper Mississippi River Valley, but boundary doesn`t
look overly convergent at this time, nor is there a tap to low level
moisture and just meager RH. Could be a dry frontal passage.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1248 PM CDT Sat Oct 19 2019

A cold front will move east through western Wisconsin this
afternoon. This front will produce showers at KRST for the next hour
and at KLSE through 19.22z.

Strong subsidence in the wake of this front will cause clearing at
KRST by 19.1930Z and at KLSE by 19.21z.

It continues to look like some fog and low stratus will develop
across western Wisconsin overnight. The main question is how west
these low clouds will get. Earlier this morning, it looked favorable
for them to get into KLSE. However, the latest RAP is looking less
favorable. In addition, the boundary layer winds have increased
which would make it less likely for valley fog development.
&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION...Boyne



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